44 ;0 &! ". ..... . ....;: .: Jil ." > .:"Øi\ '*',.::;<!*t ,!,/ \ ...... Á4:* ' ' J .. \\V :. ".r \\ . . ^ .. \ {"i.. -" t - \. Vt -4 v " .J .> . '. . .>.' @ & - . . .... ....... ,(" './<' "Dearest Elzzabeth! Have I ever told you how ravishing you look from here?" . the moon twenty years ago, NASA might have come up with a reusable spacecraft to begin with, for in 1958 it was working on plans for a more primitive space glider, called Dyna- soar, that would have been launched into orbit by rocket and would have returned by gliding on delta-shaped wings to an airfield. Though in those days, when almost nothing was known about space, it would have taken not only more tIme to develop the glider -rather than the ballistic space- craft-but also a good deal more money, the evolution of spacecraft would have been more natural and or- derly. The ballistic craft was a sort of . mutation, with few antecedents, where- as the winged spacecraft is the main evolutionary line of the rocket ship; in fact, engineers had been working on this design long before there was a space program. In Germany in the late nineteen-thirties, work was proceed- ing on the winged V-I rocket bomb, which blasted off an inclined ramp; before the end of the Second World War, the Germans were working on a winged rocket bomb that would have followed an arc into space and glided down to hit New York City, more than thirty-five hundred miles away. They also made a rocket-powered air- plane, the Messerschmitt 163, which launched a piloted glider to forty thousand feet After the war, this line of research continued in the United States, to which a number of the Ger- man experts had emigrated. The first American rocket plane was the X-I, which in October of 1947 was carried aloft in the modified bomb bay of a B-29 and released. Piloted by Captain (now General) Charles Yeager, it reached a height of forty-two thou- sand feet and became the first piloted aircraft to exceed the speed of sound (Mach 1, which varies between seven hundred and sixty m.p.h. at sea level and six hundred and sixty m.p.h. above thirty-six thousand feet; Yeager's speed was Mach 1.015 ). Yeager then glided the plane to a landing on a dry lake bed at Edwards Air Force Base, in California. The X -series rocket planes looked like little winged bombs; they had short, conventional wings of a type known as straight wings. As the planes in the X-series went higher and faster-reaching Mach 2.1 and sixty- two thousand feet, and then reaching Mach 3.2 and seventy thousand feet-the wIng design became increas- ingly swept back, to diminish atmo- spheric friction, which nevertheless caused the wings to get as hot as twelve hundred degrees. In July of 1962, Major Robert White, flying the X-IS, a descendant of Captain Yeager's craft, rocketed at a speed of almost Mach 6 to an altitude of over three hundred and fourteen thousand feet-almost above the earth's atmo- sphere and officially in space. He was not, however, the first man to attain that honor; by that time, several Soviet and American cosmonauts and astro- nauts had travelled into space by a quite different method. During the next couple of decades, as Mercury, Gemini, and Apollo cap- sules had their fling, the rocket planes mostly stayed on the ground. Still, those who had worked with them re- mained loyal to them; the day of the rocket planes would come again, they were sure. In the opinion of these partisans, it now has, even though the shuttle differs in some respects from its forerunners: it is much bigger, goes about four times as fast, and requires much more complex systems for navi- gation and heat protection. From August through October of 1977, a prototypical orbiter, the Enterprise, which was principally a test vehicle and probably won't ever be used in space, went through a series of tests